1. Field of the Invention
The present invention relates to a sealed letter formation system which forms a sealed letter with a printed matter enclosed in an envelope.
2. Description of the Related Art
In recent years, a variety of sealed letter formation systems have been developed along with expanding use of sealed letters such as direct mails. A conventional, general enclosing and sealing device (see Japanese Patent Application Laid-Open Publication No. 2005-67724, for example) included in a sealed letter formation system will be described in the following.
Conventionally, in a general enclosing and sealing device, there are provided, within the device housing, a content formation unit which folds a content sheet to form a content and an envelope formation unit which folds an envelope sheet to form an envelope. A content conveyer is provided at the entrance side of the envelope formation unit. The content conveyer feeds out a content, which has been fed out from the content formation unit, toward the envelope formation unit at a preliminarily set constant feed-timing so that the content is enclosed in an envelope being folded. A sealing unit is provided at the exit side of the envelope formation unit. The sealing unit seals the envelope fed out from the envelope formation unit with the content enclosed therein.
In such an enclosing and sealing device, the content formation unit folds a content sheet to form a content, and feeds out the content toward the content conveyer. In addition, after having positioned envelope sheet in its lateral direction (a sheet-width direction perpendicular to the conveying direction), the envelope formation unit folds the envelope sheet to form an envelope, and feeds out the envelope toward the sealing unit. While the envelope formation unit is folding the envelope sheet, the content conveyer feeds out the content toward the envelope formation unit at a preliminarily set constant feed-timing, thereby to feed out the envelope enclosed with the content toward the sealing unit. Furthermore, formation of the sealed letter is completed by sealing of the envelope by the sealing unit, and whereby the sealed matter is ejected from an ejection port side and received in a container.
Typical folding modes of an envelope include a three-fold mode in which the envelope sheet is folded at two places to form a three-layer state, and a four-fold mode in which the envelope sheet is folded at three places to form a four-layer state. A conventional enclosing and sealing device usually allows switching between the three-fold and four-fold modes via an input panel or the like provided on the device.
When making the length of an envelope in the conveying direction after the envelope is folded in a three-fold mode equal to the length of an envelope in the conveying direction after the envelope is folded in a four-fold mode, the overall size of the envelope in the four-fold mode is longer in the conveying direction compared with the envelope in the three-fold mode. Accordingly, there has been a problem that the space required for lateral-direction positioning of the envelope sheet (in the sheet-width direction) increases, which may result in an increased size of the device. In addition, since the tip of the envelope sheet is used for lateral-direction positioning of the envelope sheet, the rear edge of the sheet in the four-fold mode has a poor follow-up characteristics compared with the three-fold mode. Accordingly, there has also been a problem of a prolonged processing time for positioning, which may result in a decreased productivity. In order to shorten the processing time, it is required to newly provide a mechanism for positioning of contents, which may result in further increase in size and cost of the device.